• Korean Journal of Soil Science and Fertilizer
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• v.32 no.2
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• pp.140-146
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• 1999

This research was conducted to investigate the changes of $NH_4-N$ in soil, nitrogen uptake by rice plant, nitrogen-use efficiency and rice yield by the application of latex coated urea(LCU) on 10-day old seedling transplanted with machine on paddy field, Jeonbuk series at the Honam area, from 1997 to 1998. Almost all nitrogen in LCU application as basal dressing in whole layer was dissolved until maximum tiller stage, the maximum dissolution time was productive tiller stage and $NH_4-N$ content of conventional plot with surface application of fertilizer were lowered at full periods. Nitrogen deficiency symptom were appeared at heading stage of 31.6% SPAD value and nitrogen concentration was 1.29% shoot. From heading stage to ripening stage, the necessity of nitrogen-fertilizer was $2.9kg\;ha^{-1}$ for the conventional split application plot and $11.9kg\;ha^{-1}$ for the whole layer application plot of LCU basal dressing. Nitrogen-use efficiency was higher at the LCU application plot than the conventional application plot and was increased for 12.7% by fertilization at panicle forming stage. The additional fertilization at panicle forming stage to basal dressing of LCU causes 13% yield increase.

• Korean Journal of Soil Science and Fertilizer
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• v.35 no.4
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• pp.216-222
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• 2002

Field experiments were conducted to investigate the effect of various cultural practices on methane($CH_4$) emission in tillage and no-tillage practice in a clayey paddy soil from 1998 to 2000. The factors evaluated in tillage and no-tillage methods were types of nitrogen fertilizers, application method of chemical fertilizers, rice straw application and cultivation method. Of the nitrogen fertilizers, the amount of $CH_4$ emission in ammonium sulfate plot was the lowest, regardless of tillage and the application method. 26.4~41.1% of reduction by ammonium sulfate compared with urea. But in no-tillage which have problem of poor rice yield than tillage, coated urea was more effective nitrogen fertilizer because that showed similar $CH_4$ emission and highest rice yield at 80% of dosage of nitrogen. No-tillage plot emitted lower $CH_4$ than tillage plot where the fertilizers were incorporated. On the contrary, no-tillage plot showed a little higher $CH_4$ emission compared with tillage plot for the surface application. When rice straw was applied, no-tillage practice reduced methane emission by 26.6% compared with tillage practice, but showing a little difference of 10.7% in no application. With cultivation method, no-tillage practice reduced methane emission 26.6% compared with tillage for the 30-d-old seedling transplanting. But for the dry direct seeding practice, no-tillage was a less effective because considerable amounts of rice straw incorporated by tillage were more decomposed aerobically in the soil and emitted as $CO_2$ to the atmosphere with flooding in no-tillage soil.

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.4
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• pp.342-349
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• 1998

In order to evaluate the effects of nitrogen (N) rate and application method on the recovery of N fertilizer applied in spring and summer by Satsuma mandarins (cv. Miyakawa Wase), N as urea was surface-applied at the rates of 50 (applied with 20 mm water; 50% N application) and 100% (three treatments; applied as solid, with 5 or 20 mm water) of the recommended rate ($150kg\;ha^{-1}\;yr^{-1}$) on 25 March and 12 June with an application ratio of 50 and 20%. The labeled N was applied only once in spring or summer. There were no differences among the four treatments in fruit yield, fruit quality except acid content of juice, and N content of leaves. The recovery of fertilizer N applied in spring by a tree ranged from 7.8 to 8.3% and that of N applied in summer ranged from 11.3 to 14.2% at the three recommended N rates and was 18.0% for the 50% N application. The recovery of fertilizer N applied in spring in the upper 40 cm of soil ranged from 32.1 to 37.7% at the three recommended N rates and was 55.8% at the 50% N application. For N applied in summer, it was 69.8% for surface application of the recommended N rate and ranged from 80.7 to 84.4% for the three N applications with water. The total (tree+soil) recovery of N fertilizer applied in spring was highest (64.1%) for the 50% N application and ranged from 40.3 to 45.5% for the three recommended N rates. The total recovery of N fertilizer applied in summer was also highest (99.4%) for the 50% N application and tended to be higher for the application of N with water than surface application and to increase with increasing irrigation amount of N application.

• Nuclear Engineering and Technology
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• v.11 no.1
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• pp.47-54
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• 1979

A field experiment has been carried out to evaluate the residual effect of zinc fertilizers by rice plant grown under flooded conditions in the field. The results obtained are summarized as fellows ; Residual effect of zinc fertilizers on yields of rough and hulled grains showed slight increases. Effect of zinc application methods on yields of the grains were shown that zinc mixed treatment could be more effectively utilized than treatment of zinc on the soil surface. In case of levels of zinc application, 5 kg zinc per hectare represented high yields of the grains than those obtained from 10kg and 20kg zinc placement per hectare respectively. Regarding the form of zinc fertilizers, the urea-zinc complex showed less effective on yields of the grains than did the zinc sulfate. This phenomenon was consistent with the previous result. Yields of total zinc in rice plant grown on the rice straw added soils (Treatment No. 2 and 8) and the urea-zinc complex treated soil were increased markedly as compared to those data obtained from the previous year. The percentage of zinc derived from fertilizer decreased largely as compared to that of the first year crop. The yield of fertilizer zinc in rice plant decreased slightly in the most zinc treatments but in the case of treatments of zinc mixed with the straw added soil and the urea-zinc complex increased reversely as compared to the previous results. The mixed application of zinc with soil showed higher yield of fertilizer zinc than the soil surface placement. Approximately from 4.6 to 24.3 per cent of zinc taken up by rice plants were derived from the fertilizer zinc. Zinc fertilizer use efficiency ranged from 0.213 to 0.584 per cent when 5 kg zinc per hectare applied.

• Nuclear Engineering and Technology
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• v.10 no.4
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• pp.215-222
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• 1978

Using tracer technique of $^{65}Zn$, a field experiment has been carried out to evaluate the efficiency of zinc fertilizer by rice plant grown under flooded conditions. The treatments include zinc slufate mixed throughout the soil with and without organic matter, combined urea-zinc fertilizer (N: 37.7%, Zn: 3.1%), and surface application at transplaning and two weeks after transplanting at the rate of 5kg Zn/ha respectively. Other treatments were zinc sulfate mixed throughout the soil at the rate of 10 kg and 20 kg Zn/ha respectively. Root dipping in 2 % ZnO suspension, only organic matter added, and control were also included. There was not much difference in rough grain yield between zinc levels and different application methods, but the highest yield was obtained from the treatment of the root dipping in 2% ZnO suspension. Among the 5kg Zn/ha treatments, the highest total zinc yield was observed from the zinc mixed throughout the soil. The organic matter treatment seemed to reduce the zinc fertilizer efficiency. In case of the zinc fertilizer levels, 5kg Zn/ha mixed throughout the soil showed the highest zinc fertilizer efficiency as compared with 10kg and 20kg Zn/ha treatments.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.2
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• pp.132-139
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• 1999

A field experiment was conducted at Cheju from early March 1998 to early March 1999 to evaluate the effects of foliar applied urea on leaf N content and N recovery in satsuma mandarins (Citrus unshiu Marc.). Seven years old 'Okitsu Wase' trees received foliar spray of urea (22 or 43 g N $tree^{-1}yr^{-1}$) or soil application of urea (86 g N $tree^{-1}yr^{-1}$). 56% of N was applied in spring, 11% in summer and 33% in fall. There were seven trees per N treatment and two trees per N treatment received $^{15}N$-labeled urea in spring and summer to determine N recovery. There were no differences between the treatments for fruit yield and its quality. Nitrogen content of spring flush leaf blades up to early September was greater for trees received foliar spray comparing with soil application but was not greatly affected by any treatment after mid-November. The recovery of fertilizer N in various parts of trees receiving foliar spray of 22 g N $tree^{-1}yr^{-1}$ was greatest, followed by receiving foliar spray of 43 g N and soil application of 86 g N. The recovery of fertilizer N in tree was 29.2 and 17.7% for foliar spray of 22 and 43 g N $tree^{-1}yr^{-1}$, respectively and 8.0% for soil application of 86 g N $tree^{-1}yr^{-1}$. The recovery of fertilizer N in the upper 40 cm of soil was 50.3, 45.6, and 51.8% for foliar spray of 22 and 43 g N $tree^{-1}yr^{-1}$, and soil application of 86 g N $tree^{-1}yr^{-1}$ respectively. The total (tree, fallen leaves, winter weeds, and soil) recovery of fertilizer N was 81.8, 65.1, and 60.6% for foliar spray of 22 and 43 g N $tree^{-1}yr^{-1}$, and soil application of 86 g N $tree^{-1}yr^{-1}$, respectively.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.4
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• pp.315-320
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• 1986

The investigation was conducted to find out amounts and ratios of N, P and K fertilizers applied on rice in 410 farmers' fields. The application ranges of N, P and K fertilizers, respectively, were 15.4-16.3, 7.6-8.0 and 8.2-8.5kg/10a for high yielding varieties, and 13.1-13.8, 7.0-7.1 and 6.4-7.7kg/10a for ordinary varieties. N fertilizer was applied in the ratio of 56% at basal dressing, 34% at tillering, 9% at panicle formation and 1% at heading stage. The amounts of soil amendment application were 179-192kg/10a for silicate, 1,031-1,360kg/10a for compost, 420-540kg/10a for rice straw, and 17.8-25.2 ton/10a for red earth.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.1
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• pp.56-63
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• 1983

On a newly reclaimed soil, an experiment was carried out for the elucidation of proper rate of phosphorus fertilizer and application method to increase soybean yield in Honam area. 1. The yield was high in whole layer placement of phosphorus fertilizer and low in deep placement. 2. Broadcasting with 15% of phosphate fixation coefficent and whole layer and deep placement of fertilizer with 10% of phosphate fixation coefficent showed maximum yield. 3. Large application of phosphate increased stem diameter and number of blanches and podes. 4. Application of phosphorus fertilizer increased phosphate content in soil from 9 ppm to 48-223 ppm and contents of bases 5. Significant positive correlation was obtained between soybean yield and phosphorus uptake amount.

• Korean Journal of Soil Science and Fertilizer
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• v.10 no.1
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• pp.61-67
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• 1977

A study was conducted in order to compare the topdressing method of the conventional fertilizers as control and the deep application method of the ball complex fertilizer newly developed. The ball complex fertilizer consisted of 5% of nitrogen, 5% of phosphorus, and 7% of potassium. Basal application of nitrogen for the rice plant was the same for both control plots and ball complex plots. One ball complex fertilizer per four hills was applied at depth of 12~13cm 35days before heading stage while control plot received three times topdressing at different growth stages as usual practice. The results obtained were as follows. 1. The ball complex fertilizer applied in the soil was continuously utilized by the rice plants until harvest time while nitrogen and potassium uptake of control plots was reduced rapidly after heading stage. Daily uptake of nitrogen and potassium per hill at maturing stage were 0.45mg and 0.68mg in control plots, but 4.80mg and 7.0mg respectively in ball complex plots. 2. Dry matter productivity of the rice plant in control plots, well coinciding with nutrients uptake pattern, was maximum just after heading stage decreased at maturing stage. But dry matter productivity in ball complex plots was much higher at maturing stage than at heading stage. 3. Ball complex application increased effective tillering rate, causing higher panicle number per hill. 4. Ball complex application brought about 528kg/10a of hulled grain yield while the conventional practice 423kg/10a. 5. Deep application of ball complex was superior to usual practice in terms of yield components such as panicle number per hill, filled grain number per panicle, maturing rate, and 1,000 grain weight. 6. From the morphological characteristics point of view, the deep application of ball complex made the flag leaf and the 2nd leaf heavier, larger and broader as compared to control treatment. 7. It is considered that by applying the ball complex fertilizer at depth of 12~13cm sufficient amount of nitrogen and potassium could be utilized by rice plants during the maturing stage and assimilated in the leaf blade, consequently making the flag leaf and the 2nd leaf bigger and healthier. The fact can easily explain that the ball complex plots had higher capacity of photosynthesis, less discoloration of lower leaves, bigger leaf area index, and better grain yield as compared to the conventional practice. In conclusion the deep application method of the ball complex fertilizer was superior to the routine topdressing method of the usual fertilizers.

• Korean Journal of Soil Science and Fertilizer
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• v.24 no.2
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• pp.102-108
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• 1991

A field experiment with microplots(D.20cm, L. 85cm) was conducted to obtain quantitative information on the downward movement of nutrients applied to the soils by different amount of irrigation water. The microplots were installed by embedding PVC column(D. 20cm, L. 90cm) filled with sieved soils in the field. Urea, fused and superphosphate, and KCl were broadcasted over the soil in the microplots and surface layer was covered with lime-amended soils. Microplots were removed 1 week after water application and analysed for Cl, $NH_4$ and $NO_3-N$, Bray 1-P and exchangeable cations of Ca, Mg, and K in each segment. Effect of irrigation rate on the movement of these ions were evaluated with the mean downward movement(MDM) determined with nutrient concentration of each segment and the distance to the segment from the site fertilized. For the nutrient studied, MDM was linearly related to the amount of water applied. When one pore volume of water needed for 0.1 bar soil moisture tension was applied, MDM(cm), computed as the piston front of applied water advanced 10cm, was found to be in the order; Cl, 7.52>Inorganic N, 6.03> K, 3.50> Mg, 2.69>Ca, 1.19>P, 0.29. After the downward movement of applied nutrients soil pH seemed to decrease with irrigation in the surface layer(0-15cm) and increase in the subsurface layer. It was also found that ammonium-nitrogen evolved from urea hydrolysis was more effective in raising the subsoil pH rather than the exchangeable Ca and Mg.